The board wears a picture — background becomes a mapping, and the window chrome follows it under a thin frost

background is {color:, image:} and only a mapping at every level; the board's image paints the full window under a transparent title bar, with a thin-material frost strip keeping the chrome legible and the standard accommodations intact.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

KanbanTests/VisualAccommodationsTests.swift

@@ -262,13 +262,15 @@ struct IncreaseContrastTests {
 @Suite("Accommodations ▸ Reduce Transparency")
 struct ReduceTransparencyTests {
 
-    /// "Glass underlays go solid, wherever they appear" (10-accessibility.md). The board's one
-    /// surviving material is the transient search bar's `.bar` — the design's own example, the card
-    /// face carousel's page dots, died with the carousel (03-board-ui.md § Card face).
-    @Test("The one glass underlay goes solid")
+    /// "Glass underlays go solid, wherever they appear" (10-accessibility.md). The board carries
+    /// two materials — the transient search bar's `.bar` and the backdrop's title-bar frost — and
+    /// the rule is one rule: both take the same solid, whatever their weights without it.
+    @Test("Both glass underlays go solid")
     func glassGoesSolid() {
         #expect(Accommodations.underlay(reduceTransparency: false) == .glass)
         #expect(Accommodations.underlay(reduceTransparency: true) == .solid)
+        #expect(Accommodations.frost(reduceTransparency: false) == .frost)
+        #expect(Accommodations.frost(reduceTransparency: true) == .solid)
     }
 
     /// The washes are not glass — they composite at an alpha rather than sampling a backdrop — but